The use of sophisticated personal communication devices (PCDs) such as pagers, that can display and respond to alphanumeric messages, continues to grow more and more common. Alphanumeric messages that are sent to such PCDs are generated by a machine or a person. Examples of machine generated messages are a news update and a stock market update. Messages generated by persons can be composed and sent using a computer connected to a network, or by calling a message entry service staffed by operators who enter the message, or by using a standard telephone instrument, or by using another PCD. The ability to compose alphanumeric messages by using a standard telephone instrument is highly desirable because telephone instruments are ubiquitous and familiar to most people, but adapting a telephone keypad to compose an alphanumeric message has required ingenuity because the telephone keypad was developed for numeric, not alphanumeric entry. Known techniques exist for using a standard telephone keypad for composition of alphanumeric characters. An example of a known technique involves an identification by the user of which of the three or four alphanumeric characters on one key is to be entered into the message. For example, in one method, a key is keyed one to four times within a short time to indicate which of four characters is to be entered. In another method, a key is held depressed while the characters it represents are presented to the user, one at a time (either visually or audibly), and released when the desired character is presented. While these two techniques allow an alphanumeric message to be composed successfully, they are unnatural and difficult for many callers.
Thus, what is needed is a technique for composing an alphanumeric message from a standard telephone keypad that reliable and natural.